Enzalutamide Antitumour Activity Against Metastatic Castration-resistant Prostate Cancer Previously Treated with Docetaxel and Abiraterone: A Multicentre Analysis.

The degree of antitumour activity of enzalutamide following disease progression on docetaxel and abiraterone remains controversial. To examine the effect of enzalutamide in patients progressing following taxane-based chemotherapy and abiraterone. Metastatic castration-resistant prostate cancer patients entering one of four European compassionate use programmes of enzalutamide. The primary end point was overall survival (OS). Secondary end points were association between OS and posttreatment prostate-specific antigen (PSA) kinetics, patient characteristics, and progression-free survival, respectively. Kaplan-Meier survival analysis and Cox proportional hazard analysis were performed. We identified 137 patients who prior to enzalutamide had progressed following a median of eight cycles of docetaxel and seven courses of abiraterone. The median time on enzalutamide was 3.2 mo; median OS from the time patients started enzalutamide was 8.3 mo (95% confidence interval, 6.8-9.8). Only 45 (38%) and 22 (18%) patients had PSA declines (unconfirmed) >30% and 50%, respectively. Patients who had more than 30% or 50% falls in PSA had improved survival compared with patients who had no such PSA fall (11.4 mo vs 7.1 mo; p=0.001 and 12.6 vs 7.4 mo; p=0.007, respectively). Poor performance status and low haemoglobin was negatively associated with OS. Median OS on enzalutamide following disease progression on taxane-based chemotherapy and abiraterone was modest, but patients who experience a PSA decline >30% or 50%, respectively, with enzalutamide in this setting had longer survival. Enzalutamide produces modest prostate-specific antigen (PSA) responses in patients progressing following chemotherapy and abiraterone. Despite a modest PSA response, survival may still be improved.

Brasso K ，Thomsen FB ，Schrader AJ ，Schmid SC ，Lorente D ，Retz M ，Merseburger AS ，von Klot CA ，Boegemann M ，de Bono J ... -  《-》

Cabazitaxel Remains Active in Patients Progressing After Docetaxel Followed by Novel Androgen Receptor Pathway Targeted Therapies.

Cabazitaxel, abiraterone acetate (AA), and enzalutamide have been approved for the treatment of patients with metastatic castration-resistant prostate cancer (mCRPC) following docetaxel chemotherapy. Whether taxanes and next-generation androgen receptor (AR) axis inhibitors are cross-resistant or not is a subject of debate. To evaluate the antitumour activity of cabazitaxel in mCRPC pretreated with abiraterone or enzalutamide. The antitumour activity of cabazitaxel was assessed in patients with mCRPC and progressive disease after treatment with docetaxel and AA. In parallel, cabazitaxel antitumour activity was studied in enzalutamide-resistant models. Changes in prostate-specific antigen (PSA) levels and progression-free survival were used to determine the activity of cabazitaxel treatment. Cell proliferation, immunofluorescence, and AR transactivation assay were used in enzalutamide-resistant models. A total of 79 patients who had progressive mCRPC after docetaxel (median: 8 cycles; range: 4-12 mo), and AA (median: 4.8 mo; range:1-55 mo) received cabazitaxel 25mg/m(2) every 3 weeks (median: 6 cycles; range:1-15 cycles). A PSA decline ≥30% was achieved in 48 patients (62%; 95% confidence interval [CI], 51-73), and a decline ≥50% was achieved in 28 patients (35%; 95% CI, 25-47). The median progression-free survival and overall survival were 4.4 and 10.9 mo, respectively. In vitro, cabazitaxel decreased cell viability in both enzalutamide-sensitive and enzalutamide-resistant prostate cancer cells within the same range of concentrations. PC3, an AR-negative cell line, exhibited similar sensitivity to cabazitaxel. Cabazitaxel and AR-pathway inhibitors are not cross-resistant. Preclinical data suggest that cabazitaxel activity does not act mainly through AR axis inhibition. The antitumour activity of cabazitaxel, a chemotherapy agent, was studied in prostate cancer resistant to conventional hormonal therapy and to more recent endocrine therapies (abiraterone or enzalutamide). Cabazitaxel retained anticancer activity in more than half of the cases.

Al Nakouzi N ，Le Moulec S ，Albigès L ，Wang C ，Beuzeboc P ，Gross-Goupil M ，de La Motte Rouge T ，Guillot A ，Gajda D ，Massard C ，Gleave M ，Fizazi K ，Loriot Y ... -  《-》

Androgen Receptor Splice Variant 7 and Efficacy of Taxane Chemotherapy in Patients With Metastatic Castration-Resistant Prostate Cancer.

Antonarakis ES ，Lu C ，Luber B ，Wang H ，Chen Y ，Nakazawa M ，Nadal R ，Paller CJ ，Denmeade SR ，Carducci MA ，Eisenberger MA ，Luo J ... -  《-》

Efficacy of enzalutamide following abiraterone acetate in chemotherapy-naive metastatic castration-resistant prostate cancer patients.

The activity of enzalutamide after prior treatment with both abiraterone acetate (abiraterone) and docetaxel has been examined in several retrospective studies. However, limited data are available on the efficacy of enzalutamide following abiraterone in chemotherapy-naive patients with metastatic castration-resistant prostate cancer (mCRPC). To compare the activity of enzalutamide after abiraterone in docetaxel-experienced and docetaxel-naive mCRPC patients. The British Columbia Cancer Agency Cancer Registry was searched for mCRPC patients who received enzalutamide after prior abiraterone. Clinicopathologic characteristics, confirmed prostate-specific antigen (PSA) response rates (PSA decline ≥ 50% confirmed ≥ 3 wk later), and survival data were collected. Outcomes on enzalutamide were compared between docetaxel-experienced and docetaxel-naive patients using chi-square for PSA response and log-rank test for time to PSA progression and overall survival (OS). Univariate analysis was performed to identify variables associated with confirmed PSA response on enzalutamide, using either chi-square for categorical variables or logistic regression for continuous variables. A total of 115 patients received enzalutamide after abiraterone: 68 had received prior docetaxel and 47 were docetaxel naive. Median time on enzalutamide was 4.1 mo. Confirmed PSA response rates (22% vs 26%; p=0.8), median time to radiologic/clinical progression (4.6 mo vs 6.6 mo; p=0.6), and median OS (10.6 mo vs 8.6 mo; p=0.2) did not differ significantly between docetaxel-experienced and docetaxel-naive patients. No clinical variables (including prior response to abiraterone) were found to associate significantly with confirmed PSA response to enzalutamide. Antitumour activity of enzalutamide following abiraterone was limited in mCRPC patients irrespective of prior docetaxel use. Identifying clinical and molecular factors predictive of response to enzalutamide remains a high priority for future research. We looked at the effectiveness of enzalutamide after abiraterone acetate for treatment of advanced prostate cancer. We found that patients who had received docetaxel chemotherapy before abiraterone gained similar benefit from enzalutamide compared with patients who had not received docetaxel. These results suggest that earlier treatment with docetaxel does not have a large impact on the activity of enzalutamide after abiraterone.

Azad AA ，Eigl BJ ，Murray RN ，Kollmannsberger C ，Chi KN ... -  《-》

Exploring the Clinical Benefit of Docetaxel or Enzalutamide After Disease Progression During Abiraterone Acetate and Prednisone Treatment in Men With Metastatic Castration-Resistant Prostate Cancer.

Abiraterone acetate (AA) has demonstrated improved outcomes in men with metastatic castration-resistant prostate cancer (mCRPC). However, data are lacking on the effect of AA on subsequent efficacy of enzalutamide or docetaxel. We included men with mCRPC who received AA and subsequent enzalutamide or docetaxel by August 12, 2013. Patients were separated into 3 groups: group A, treated with AA then enzalutamide before chemotherapy; group B, treated with AA then docetaxel; and group C, treated with AA and enzalutamide after chemotherapy. The primary objective was to describe the response and overall survival with subsequent therapy. There were 28 evaluable patients who received enzalutamide after AA (9 in group A and 19 in group C) and 13 patients who received docetaxel after AA (group B). Group A patients had more visceral disease and higher baseline prostate-specific antigen (PSA) levels, and group C men had a higher level of pain and multiple poor prognostic features. Median progression-free survival was 3.6, 5.1, and 2.8 months, respectively, and median overall survival was 8.5, not reached, and 9.6 months, respectively. A ≥ 50% PSA decline was achieved in 11%, 63%, and 5% of group A, B, and C patients, respectively. Radiographic or clinical progression as best response was noted in 55.5%, 30.8%, and 68.4% in each respective group. In this chart review of consecutive men with progressive mCRPC after AA, we found modest activity for enzalutamide and docetaxel, with clear cross-resistance for AA and enzalutamide. These data might inform the complex treatment decisions after AA treatment.

Zhang T ，Dhawan MS ，Healy P ，George DJ ，Harrison MR ，Oldan J ，Chin B ，Armstrong AJ ... -  《-》